Inside ComputeParticlePosition the position is multiplied by the view and projection matrix.

[CODE]
// Vertex shader helper for computing the position of a particle.
float4 ComputeParticlePosition(float3 position, float3 velocity,
float age, float normalizedAge)
{
float startVelocity = length(velocity);
// Work out how fast the particle should be moving at the end of its life,
// by applying a constant scaling factor to its starting velocity.
float endVelocity = startVelocity * EndVelocity;

// Our particles have constant acceleration, so given a starting velocity
// S and ending velocity E, at time T their velocity should be S + (E-S)*T.
// The particle position is the sum of this velocity over the range 0 to T.
// To compute the position directly, we must integrate the velocity
// equation. Integrating S + (E-S)*T for T produces S*T + (E-S)*T*T/2.
float velocityIntegral = startVelocity * normalizedAge +
(endVelocity - startVelocity) * normalizedAge *
normalizedAge / 2;